Composites made of feather fiber (Ff), kraft pulp fiber (Pf), polypropylene (PP), and maleic anhydride modified polypropylene (MaPP) were tested in tension and three-point bend tests. Composite panels were compression molded from multiple plies of nonwoven, fabric-like prepreg manufactured with wetlay papermaking equipment. Composites containing all four materials were manufactured with MaPP substitutions for PP of 0-10 wt % at 2 wt % increments. The best mechanical properties were observed with a substitution of 8 wt % MaPP. Composites containing either Pf or Ff were manufactured with MaPP substitutions for PP of 0, 4, and 8 wt %; mechanical properties improved with increases in MaPP content. The improvements in mechanical properties were attributed to fiber/matrix interface improvement by the addition of MaPP. Scanning electron microscopy revealed evidence of improved interfacial bonding on the tensile fracture surfaces. (C) 2004 Wiley Periodicals, Inc.